What kind of SPI did you use?
Which SPI_Master or SPI(SCB mode)?
I guess it was SPI_Master.
In PSoC4, Usual SPI module can't assign to dedicated Pins.
Besides, SPI(SCB mode) must assign to dedicated Pins.
That shows pin assignment dialog in Blue print.
Data sheet of SPI(SCB mode) say
The interface specific pins are buried inside component because
these pins use dedicated connections and are not routable as general purpose signals.
See the I/O System section in chip Technical Reference Manual (TRM)
for more information.
In the TRM the following is stated -
7.17 Restrictions on Port 4
Port 4 does not have a dedicated port-adapter (Port Adapter Block on page 161). Therefore, none of the port 4 pins can be
routed through the DSI. However, port 4 pins can still be used as a firmware pin, LCD_COM, LCD_SEG or can be connected
to the SCB block through the HSIOM.